The present invention relates generally to nonimaging radiant energy collectors and concentrators, and more particularly to an apparatus and a method for constructing a plurality of longitudinally extending, generally trough-shaped channels which approximate the ideal shape for such nonimaging concentrators. Pertinent art in connection with nonimaging concentrators include an article entitled "Principles of Cylindrical Concentrators for Solar Energy" by Winston and Hinterberger, published in Solar Energy, Vol. 17 pp. 255-258, Pergamon Press 1975, in which the authors describe the ideal cylindrical light collector or concentrator, and the necessary or required shape of the channel side walls for maximum concentration of the radiant energy entering the channel through an entrance aperture at the exit aperture. To the same effect, see also the U.S. Pat. Nos. 3,923,381 and 4,003,638 issued on Dec. 2, 1975 and Jan. 18, 1977, respectively, to Winston.
The ideal, nonimaging concentrator described in the above referenced article and patents (hereinafter also referred to as the Winston-type concentrator) has a pair of channel side walls which are precisely defined by mathematical expressions. To fabricate concentrators having such side walls is expensive because the specified side wall shape requires that the channel be cast or extruded, using a precise form, after which the side walls have to be machined and polished to provide the necessary facing reflective surfaces. Further, such castings or extrusions are usually thick to provide the necessary structural rigidity for an elongated channel, which further adds to the expense of fabrication and installation. Still further, the material from which these castings or extrusions are made must retain its reflectivity under constant exposure to the weather, which rules out many an inexpensive casting or extrusion material.
Since energy conservation, and particularly the utilization of solar energy as an alternate energy source, are most desirable at this time, and much effort is directed towards achieving this goal, it is surprising that the nonimaging radiant energy concentrator has not come into more common use. One of the explanations for the present lack of popularity of such concentrators is the cost factor, which, at this time, makes the expense of such concentrators substantially greater than that of solar panels which utilize, at least in the majority of instances, neither an imaging nor a nonimaging collector or concentrator structure.